Cam interrupted sealing jaws for product stripping

ABSTRACT

An arrangement for stripping a packaging tube to remove product from the seal area is provided wherein the stripping plates may be conveniently mounted on the sealing jaws and brought into stripping engagement by single pneumatic cylinder and interrupter cam arrangement. Specifically, a follower roller is carried by the toggle linkage and cylinder that actuates the sealing jaws and said roller engages a stationary cam mounted on the frame of the machine to interrupt the inward movement of the jaws short of sealing engagement; i.e., in the stripping position. After stripping, the follower roller passes over a sloping exit section of the dam for controlled release of the sealing jaws to the sealing and drawing out position. The cam assembly is made of a base member having a central channel for slidably receiving an elongated cam element. The cam element is cushioned by a resilient pad to absorb the shock of the engagement by the follower roller; the cam element being held on the base member by a pin and slot arrangement.

United States Patent Henry et al.

[ 51 Aug. 22, 1972 [54] CAM INTERRUPTED SEALING JAWS FOR PRODUCTSTRIPPING [72] Inventors: Nelson R. Henry; Donald R. Middour, both ofDecatur, Ga.

[73] Assignee: The Woodman Company, Inc.,

Decatur, Ga.

221 Filed: July 9, 1970 211 Appl.No.: 53,391

52 u.s.c1 ..s3/1s0, 53/373 [51] Int. Cl. ..B65b 51/30 58 FieldoiSearch..53/28, 190,182,373

[56] References Cited UNITED STATES PATENTS 3,347,015 10/1967 Nuttingetal ..53/l82 2,966,021 12/1960 Lane etal ..53/l82 3,027,695 4/1962Leasure ..53/28 Primary ExaminerTheron E. Condon AssistantExaminer-Eugene F. Desmond Attorney-Lowe and King [57] ABSTRACT Anarrangement for stripping a packaging tube to remove product from theseal area is provided wherein the stripping plates may be convenientlymounted on the sealing jaws and brought into stripping engagement bysingle pneumatic cylinder and interrupter cam arrangement. Specifically,a follower roller is carried by the toggle linkage and cylinder thatactuates the sealing jaws and said roller engages a stationary cammounted on the frame of the machine to interrupt the inward movement ofthe jaws short of sealing engagement; i.e., in the stripping position.After stripping, the follower roller passes over a sloping exit sectionof the dam for controlled release of the sealing jaws to the sealing anddrawing out position. The cam assembly is made of a base member having acentral channel for slidably receiving an elongated cam element. The camelement is cushioned by a resilient pad to absorb the shock of theengagement by the follower roller; the cam element being held on thebase member by a pin and slot arrangement.

10 Claims, 5 Drawing Figures PATENTEDmczz I972 SHEET 1 OF 2 xrrozA/frsCAM INTERRUPTED SEALING JAWS FOR PRODUCT STRIPPING The present inventionrelates to packaging machines and, more particularly, to an improvedproduct stripping apparatus for reciprocatory sealing jaws utilized toform successive packages from a tube of packaging film. OF THE INVENTIONIn a form and fill packaging system, packaging film or material is fedfrom a roll and transformed into a tube by passing over a former andthen heat sealing the opposite longitudinal edges together. A pair ofheatsealing jaws are next brought together against the tube to form thetransverse seals, thereby completing the pillow-like package below byforming the top seal thereof, and simultaneously forming the bottom sealfor the next package above. After each package has been formed, thecarriage for the sealing jaws moves downwardly to draw out anotherpackage length of film and the package below is separated by cuttingacross the sealed area, whereupon the operation is repeated for the nextpackage.

Before each transverse seal is formed by the sealing jaws, the productbeing packaged is inserted through the top opening of the tube. Thelength of the package is made so as to be just long enough toaccommodate the quantity of product in order to conserve packagingmaterial and to make the package as small as possible for easierhandling. Under normal circumstances, the product must thus be settledinto a compact mass in order to fit the confined space of the package.Under most circumstances, we have found that the most efficient settlingaction is performed by a Vibrating Clamp Product Settler, disclosed andclaimed in copending application of that title, Ser. No. 18,934, filedMar. 12, 1970, continuation-in-part of Ser. No. 714,862, element Mar.21, 1968. This vibrating settling action assures that no product is leftin the seal area to cause a defective seal and at the same time preventsbreakage of the product.

However, in packaging certain products which are extremely bulky, suchas large diameter potato chips, it is still desirable to utilize theolder method of clearing the seal area by stripping along the tube justbelow the sealing jaw and accept the breakage of the product attendantto this method. Thus, as is well known, a pair of stripping plates aremounted on the bottom of the sealing jaws and project outwardly from theface of the jaws. The sealing jaws are brought together in two steps asthe carriage is moving downwardly; first, just sufficiently to bring thestripping plates into engagement to flatten the tube to strip theproduct, and second, the final closing movement of the jaws together toform the seal and draw out the next package length. Previously, thistwo-stage action has been performed by a number of arrangements, such asby providing an actuating cylinder wherein double concentric piston rodsare provided; the initial travel being to actuation of one piston rodalong its length and the final movement being by movement of the otherpiston rod. This arrangement and the others of the prior art necessitatethe use of a relatively expensive fluid handling system includingmultiple servo valves to operate the cylinder in sequence and anelectrical operating system to control the valves.

Thus, there is a need for a simplified and more efficient strippingarrangement for those packaging machines requiring the same, and it is amain object of the present invention to provide such a system.

It is another object of the present invention to provide a system foroperating sealing jaws with strippers in the required two-step sequencewithout the use of additional fluid and electrical systems, servo valvesor microswitches.

It is still another object of the present invention to provide sealingjaws with stripper arrangement that relies on the simple principle ofinterruption of the normal jaw travel to perform the stripping step withsubsequent release to perform the sealing and drawing out step.

BRIEF DESCRIPTION OF THE INVENTION The sealing jaws are mounted on acarriage for actuating movement toward and away from each other to formthe transverse seals in a tube of packaging material. The sealing jawshave resilient stripper plates below and extending beyond said sealingjaws. The jaws have operating movement in the direction of thelongitudinal axis of the tube so as to strip the product and then sealand draw out a new package length. In accordance with the preferredembodiment of the invention disclosed, a cam is mounted in a stationaryposition on the machine frame adjacent the rear of the sealing carriage.A follower roller is carried by the end of the actuating cylinder and asthe cylinder is extended at the top of carriage is first moved from itsuppermost position downwardly, only stripping of the product occurs.Then, as the sealing carriage is moved further downwardly, the rollerleaves the cam surface whereby the final or second portion of the inwardsealing jaw travel is accomplished and the sealing occurs.

Preferably, the sealing jaws are actuated by a single pneumatic cylinderthrough a toggle linkage arrangement described and claimed in thecopending application, entitled Sealing Carriage, Ser. No. 863,834,filed Oct. 6, 1969, now U.S. Pat. No. 3,616,087, issued Oct. 26, 1971,of which we are coinventors and which is assigned to the same assigneeas the present application. The toggle arrangement of that invention isparticularly suited for use with the stripping apparatus of the presentinvention since the velocity of the sealing jaws nearing the strippingposition is reduced and thus the momentum of the traveling linkage andjaws is proportionally reduced. This reduction in momentumadvantageously reduces the initial impact or shock force of the followerroller engaging the cam.

Furthermore, the construction of the cam is such as to further reducethe shock or impact of the parts com- .ing together. The cam assemblyincludes a base member having an upstanding channel along the centerthereof. An elongated cam element is positioned within the channel forin-and-out movement. Behind the cam element is a rubber pad to cushionor absorb the blow of the cam follower. The upper end of the cam ismounted by a pin and slot arrangement for pivotal movement as well asmovement toward and away from the base to give further flexibility tothe cushioning action. A downwardly sloping exit section of the cam isprovided to allow controlled release of the sealing jaws to the sealingposition.

Still other objects and advantages of the present invention will becomereadily apparent to those skilled in this art from the followingdetailed description wherein I have shown and described only thepreferred embodiment of the invention, simply by way of illustration ofthe best mode contemplated by me of carrying out my invention. As willbe realized, the invention is capable of other and differentembodiments, and its several details are capable of modification invarious obvious respects, all without departing from the invention.Accordingly, the drawings-and description are to be regarded asillustrative in nature, and not as restrictive.

BRIEF DESCRIPTION OF THE DRAWINGS In the drawings:

FIG. 1 is a side view, in cross section, showing the sealing jawcarriage and the interrupter cam of the present invention mountedadjacent thereto, with the sealing jaw carriage approaching theuppermost travel position;

F IG, 2 is a cross-sectional view with the sealing jaws moved partiallyinward to the stripping position-and the carriage starting its downwardmovement;

FIG. 2a is a detailed showing of the resilient mounting of the stripperplates on the sealing jaws;

FIG. 3 is a perspective view of the interrupter cam assembly forstripping; and

FIG. 4 is a side view with a portion cut away and in cross section, ofthe cam assembly of FIG. 3.

DETAILED DESCRIPTION OF THE INVENTION Proceeding now to consider theapparatus of the invention in more detail, there is shown in FIGS. 1 and2 a carriage operable on spaced, vertical slide rods,

such as slide rod 11, to reciprocate in the up-and-down direction asnoted by the motion arrows. This reciprocatory operating movement isimparted to the carriage 10 through a carriage drive link 12, which isto be understood to be connected in any suitable manner to the maindrive of the packaging machine.

A pair of sealing jaws 15, 16 are mounted for movement toward and awayfrom each other on a pair of horizontal slide rods, such as rod 17. Thesealing jaw 15, which may be positioned at the front of the machine andthus referred to as the forward sealing jaw 15, is driven toward andaway from jaw 16 by a U- shaped link 20; whereas, the rear sealingjaw,l6 is simultaneously driven in the opposite direction toward andaway from jaw by a corresponding action link 21. As shown, the links 20,21 are connected to opposite sides of a double crank 22 by pivot pins23, 23a; the crank 22 being fixedly pivoted on pivot shaft 24, thusforming a toggle linkage with dual action, generally designated by thereference numeral T. The crank 22 may be rotated by a pneumatic powercylinder 25 which has its piston rod 26 suitably attached by a pivotjoint 27.

As shown in FIG. 2, as the sealing jaws l5, l6 approach the operativeposition, the *knee" of the two toggles at pivot pins 23, 23a is tendingtoward being straightened or going over center so that the mechanicaladvantage, and thus the sealing pressure, of the sealing jaws 15, 16 isbeing increased. However, the

momentum of the jaws 15, 16 is being reduced proportional to theincrease in mechanical advantage so as to work to the fullest advantagewith the present invention. That is, with the toggle linkage T, themaximum velocity and thus maximum momentum of the jaws 15, 16 occurs atthe start of the inward movement with the crank 22 at to the directionof travel of said jaws, and progressively decreases to substantiallyzero as the over center condition approaches. Therefore, the impact orshock force due to interruption of travel of the jaws 15, 16 is reducedover what would be experienced with comparable devices with direct drivearrangements.

As shown in FIGS. 1, 2 and 2a, stripper plates 30, 31 are mounted on thelower face of the respective sealing jaws l5, 16. As best shown in FIG.2a, the stripper plate 31 may be fixedly mounted by any number ofsuitable fasteners 32. However, the opposite stripper plate 30 ismounted for rearward sliding action by reason of slots 33 through whichthe fasteners 34 pass. A leaf spring 35 is positioned behind thestripper plate 30 to bias the sameforwardly at all times. As shown inFIG. 2a, during the stripping operation of the packaging machine, a tubeof the packaging film F is positioned between the edges of the stripperplates 30, 31 and is flattened so that the product in the lower packageis forced downwardly into the required bag space prior to the sealingoperation.

An interrupter cam assembly 40 is mounted in a stationary positionadjacent the sealing carriage l0, and in the present instance, on rearwall v41 of the packaging machine (see FIGS. 1 and 2). A follower roller42 in alignment withthe cam assembly 40 is carried by yoke 43fastened'to the'end of the piston rod 26 of the cylinder 25. When thecylinder 25 is retracted so that the sealing jaws 15, 16 are in theirwithdrawn position of FIG. 1, the follower roller 42 is positioned awayfrom the cam assembly 40, as clearly shown in FIG. 1.

When the carriage 10 is at the uppermost point in its travel cycle, itisas shown in FIG. 2, and ready to begin its downward movement asillustrated by the movement arrows. At this uppermost point, the controlof the packaging machine (not shown) is operative to actuate thecylinder 25 so as to move the sealing jaws 15, 16 toward each other. Thefollower roller 42 continues to move until the cam assembly 40 isengaged to interrupt it, which thus positions the sealing jaws close butspaced from each other short of sealing engagement, and the strippingplates 30, 31 in operative position (FIG. 2) with the film F flattenedtherebetween, as shown in FIG. 2a.

The particular construction of the cam assembly 40 forming a part of thepresent invention is shown in FIGS. 3 and 4. A base member 50 isprovided having a pair of longitudinal mounting slots 51 (only one shownin FIG. 3) positioned along-the sides thereof. These slots 51 allow theassembly 40 to be properly positioned on the wall 41v and adjusted up ordown in accordance with the length of stripping stroke desired. On thebase member 50 there is a pair of centrally located upstanding walls 52,53, which together with the base member 50 form a U-shaped channel alongthe length of the member 50. An elongated cam member 54 is guidablypositioned within the channel and adapted for limited shock absorbingmovement transverse to the longitudinal axis.

A positioning pin 55 is fixed at one end of the cam element 54 andextends through slots 56 in the walls 52, 53. The operative face of thecam element 54 is sloped downwardly at 57 in order to permit controlledrelease of the follower roller 42 from influence of the cam element 54.

A resilient pad 60 underlies the cam element 54 to perform an importantfunction in the cam assembly 40. This pad 60, which may be syntheticrubber or any other suitable resilient material, absorbs the shock orinitial impact force of the follower roller 42 hitting the upper guideedge of the cam element 54. It will be remembered that the roller 42 ismoving forwardly with substantial velocity at the moment of impact andthis dissipation of energy is very important to substantially reduce thewear of the parts and decrease the working noise of the machine. t

The pad 60 is preferably centered along the length of the cam assembly40 and is preferably the same length as the cam element 54, as shown inFIGS. 3 and 4.. The roller 42 is aligned to initially impact theoperative face of the cam' element 54 adjacent the upper edge of saidpad 60. The movement of the pin 55 along the slot 56 guaranteesresiliency and energy absorption at the impact point. As the carriagemakes its downward movement, on the stripping portion of the stroke, asshown in FIG. 2, the cam element 54 will recover slightly from theinitial impact under pressure of the pad 60. The cylinder 25 is operatedwith compressed air and serves to resiliently urge the follower rollerinto firm engagement with the cam element 54 as the carriage 10'continues to move downwardly. The downward slope or exit section 57releases the sealing jaws 15, 16 from the cam element 54 to terminatethe stripping portion of the stroke. An angle of approximately 45 hasbeen found to be suitable to allow the jaws l5, 16 to be broughttogether in a controlled fashion, as the carriage 10 6 finally moves outof the range of the cam assembly 40. Since the stripper plate 30 isresiliently mounted by the spring 35, the final movement of the sealingjaws 15, 16 to sealing engagement is accommodated by the rearwardmovement of said stripper plate 30, as noted by the arrow in FIG. 2.

From the foregoing, it can be seen that an improvement has been madewherein the stripper plates 30, 31 may, if desired, be positioneddirectly on the sealing jaws 15, 16 and properly operated with thesimpleand efficient interrupter cam assembly 40. The follower roller 42,when it engages the cam element 54, properly positions the stripperplates 30, 31 to strip the product prior to sealing. The toggle linkageT reducesthe momentum to minimize the shock of the parts comingtogether, and the use of compressed air to drive the power cylinder 25further reduces the shock. As the carriage 10 continues to movedownwardly, the

stripping operation is completed and the sloping exit section 57 permitscontrolled release of the sealing jaws 15, 16 under the bias of thecylinder 25. The cam assembly 40 is provided with a resilient pad 60 toback up the cam element 54 to also absorb the shock and cushion the blowof the follower roller 42 making contact therewith, as the jaws l5, 16are interrupted.

In this disclosure, there is shown and described only the preferredembodiment of the invention, but, as

aforementioned, it is to be understood that the invention is capable ofvarious changes or modifications within the scope of the inventiveconcept as expressed by the accompanying claims.

lclaim:

l. [n a form and fill packaging system wherein an elongated tube ofpackaging material is formed, filled, sealed and divided into individualpackages, the combination comprising a pair of sealing jaws, actuatingmeans to move said sealing jaws toward and away from said tube passingtherebetween to efiect sealing, operating means to move said sealingjaws and said tube relative to each other in the direction of thelongitudinal axis of said tube to allow drawing of a new length ofmaterial to form said packages, means interconnected with said sealingjaws, cam means to intercept said interconnection means moving from aposition free of operative engagement with said cam means andsubstantially in the direction of the inward movement of said sealingjaws toward said tube to thereby interrupt the inward movement of saidjaws short of sealing engagement, said cam means extending in thedirection of travel of the jaws along the longitudinal axis of saidtube, and means for releasing said jaws from said cam means, whereby thejaws may assume sealing engagement and the package may be sealed andformed.

2. The combination of claim 1 wherein is further pro vided a stripperplate on each of said sealing jaws,

resilient means for urging said stripper plates toward each other andinto flattening engagement with said tube when said jaws are interruptedby said cam means.

3. The combination of claim 1 wherein said cam means includes anelongated cam element, a base member mounting said cam element, andresilient means mounted between said cam element and said base memberfor absorbing the shock resulting from the interruption.

4. The combination of claim 3 wherein said base member includes asubstantially U-shaped channel to receive said cam element between theupstanding legs thereof, a pivot pin extending through one end of saidcam element and engaging cooperating elongated holes in the legs of theU-shaped base channel, and said resilient'means includes a compressiblepad mounted behind said cam element for absorbing the shock of saidinterruption.

5. The combination of claim 1 wherein said actuating means for said jawscauses a deceleration of the same when approaching sealing engagement,whereby the shock upon engagement with said cam means is minimized.

6. The combination of claim 5 wherein said actuating means comprises atoggle linkage connected to said sealing jaws and a fluid cylinder foroperating said linkage.

7. The combination of claim 6 wherein is provided a follower roller onthe end of the piston rod of said cylinder, said follower roller beingadapted to engage said cam means to cause said interruption.

8. The combination of claim 7 wherein said toggle linkage is adapted formaximum velocity of the sealing jaws when the same are substantiallyopen and progressively decreasing velocity as the sealing jaws cometogether. i

9. The combination of claim 6 wherein the fluid cylinder is operatedwith compressed air to further minimize the shock.

10. The combination of claim 1 wherein said releasing means includes asloping exit section on said cam to gradually release said jaws from theinterrupted position upon movement of the, sealing jaws along thelongitudinal axis of said tube.

1. In a form and fill packaging system wherein an elongated tube ofpackaging material is formed, filled, sealed and divided into individualpackages, the combination comprising a pair of sealing jaws, actuatingmeans to move said sealing jaws toward and away from said tube passingtherebetween to effect sealing, operating means to move said sealingjaws and said tube relative to each other in the direction of thelongitudinal axis of said tube to allow drawing of a new length ofmaterial to form said packages, means interconnected with said sealingjaws, cam means to intercept said interconnection means moving from aposition free of operative engagement with said cam means andsubstantially in the direction of the inward movement of said sealingjaws toward said tube to thereby interrupt the inward movement of saidjaws short of sealing engagement, said cam means extending in thedirection of travel of the jaws along the longitudinal axis of saidtube, and means for releasing said jaws from said cam means, whereby thejaws may assume sealing engagement and the package may be sealed andformed.
 2. The combination of claim 1 wherein is further provided astripper plate on each of said sealing jaws, resilient means for urgingsaid stripper plates toward each other and into flattening engagementwith said tube when said jaws are interrupted by said cam means.
 3. Thecombination of claim 1 wherein said cam means includes an elongated camelement, a base member mounting said cam element, and resilient meansmountEd between said cam element and said base member for absorbing theshock resulting from the interruption.
 4. The combination of claim 3wherein said base member includes a substantially U-shaped channel toreceive said cam element between the upstanding legs thereof, a pivotpin extending through one end of said cam element and engagingcooperating elongated holes in the legs of the U-shaped base channel,and said resilient means includes a compressible pad mounted behind saidcam element for absorbing the shock of said interruption.
 5. Thecombination of claim 1 wherein said actuating means for said jaws causesa deceleration of the same when approaching sealing engagement, wherebythe shock upon engagement with said cam means is minimized.
 6. Thecombination of claim 5 wherein said actuating means comprises a togglelinkage connected to said sealing jaws and a fluid cylinder foroperating said linkage.
 7. The combination of claim 6 wherein isprovided a follower roller on the end of the piston rod of saidcylinder, said follower roller being adapted to engage said cam means tocause said interruption.
 8. The combination of claim 7 wherein saidtoggle linkage is adapted for maximum velocity of the sealing jaws whenthe same are substantially open and progressively decreasing velocity asthe sealing jaws come together.
 9. The combination of claim 6 whereinthe fluid cylinder is operated with compressed air to further minimizethe shock.
 10. The combination of claim 1 wherein said releasing meansincludes a sloping exit section on said cam to gradually release saidjaws from the interrupted position upon movement of the sealing jawsalong the longitudinal axis of said tube.